Methods and apparatus for vascular protection in spinal surgery

ABSTRACT

Methods and apparatus provide for: coupling an elongate guide substantially at a first end to at least one vertebral body of a spinal column of a patient; and extending a second end of the guide to a structure of the patient spaced in an anterior direction away from the at least one vertebral body towards an entry incision.

BACKGROUND OF THE INVENTION

The present invention relates to methods and apparatus for protectingvascular structures during surgical procedures, such as during revisionsurgery to the spine.

Various surgical procedures to access to the anterior spinal column havebeen developed over the last few decades. Such procedures have permittedsurgeons to perform repair and corrective surgeries on various parts ofthe spinal column, such as repairing the motion segments of the spine.The repair procedures include arthrodesis (using allograft bone,threaded fusion cages, impaction cages, as well as plate fixation), andspine arthroplasty (using artificial intervertebral discs for replacinga part or all of a removed disc, such as elastomer discs, metal on metaldiscs, metal-poly discs, pure ceramic discs, ceramic metal or polydiscs, ball and socket discs, mechanical spring discs and hybrid discs,hydrophilic nucleus replacement, ballon polymer nucleus replacements,carbon fiber nucleus replacement)

The traditional surgical approach, for example, to a site in theanterior lumbar region the spine entails; an transperitoneal orretroperitoneal, anterior abdominal approach by means of an incisionthrough, fascia and through or around muscle planes. Exposure of theaffected spinal site also involves mobilization of the great vesselsthat lay immediately in front (anterior) of the lumbar spine. Forexample: removal of a degenerative disc and replacement with fusion cageor prosthesis requires mobilization of the vessels for exposure of thediscs. The vessels are then allowed to return to their original positionafter the spinal procedure. Depending on the anatomical location of thesurgical site, scar tissue may adhere to the aorta, vena cava and/orother retroperitoneal structures.

Normally postoperative scar tissue adheres to the vessels surroundingperi-spinal and spinal tissue obscuring the vessels as well as keyanatomical landmarks. Due to the lack of the anatomical landmarks thisscar often produces a nearly blind navigational field. The resultantscar tissue may become significantly problematic during any revisionsurgeries. While any surgery of the anterior spine requires, as aprimary effort, great care in identifying key anatomical landmarks,anterior revision surgery requires navigation (often blindly) throughvarying degrees of tenacious scar bed. Identifying vascular structuresand other key landmarks to safely commence the revision surgery poses asignificant risk to injuring sensitive structures, particularly thevascular anatomy, which can cause severe problems and even death.

The vascular structures most at risk during surgery, particularly whererevision surgery is involved, are the large veins that lie in front ofthe spine (e.g., at L1-L4: Vena Cava; and/or at L4-S1: Left and RightIliac Veins). This is so because veins are relatively flat andthin-walled, making them more susceptible to injury during the surgicalprocedure. In some instances, the evidence of a venous injury during asurgical procedure may be delayed due to vessel tamponade duringretraction. This injury may cause a patient to lose their entire bloodsupply within minutes. Arteries are also at risk during revisionsurgical procedures.

An existing publication, U.S. Patent Publication No. 2005/0177155,purports to address the issue of vessel protection during revisionsurgery. The '155 publication discloses the use of a plastic materialfor application over an annular spinal defect to minimize the amount ofscar tissue in the area and to facilitate revision surgery. Moreparticularly, a shield is configured for implantation over an anteriorportion of the spinal column, where the shield includes a sheet ofmaterial having first and second adjacent portions in the shape of a“T”. The shield is placed over a spinal surgical site on an anteriorspinal location between a spinal disk space and adjacent blood vessels.Assuming, arguendo, that the disclosure of the '155 publication enablesthe use of a shield to protect blood vessels, it does not address theissue of guiding a surgeon through, for example, varying degrees of scarbed and identifying vascular structures and other key landmarks tosafely commence the revision surgery.

As revision surgery is likely to be required for a statisticallysignificant number of patients receiving anterior spinal surgery, and assuch surgery is potentially life-threatening to a patient, there areneeds in the art for new methods and apparatus for protecting vascularstructures during surgical procedures, particularly revision anteriorsurgery to the spine. This is particularly true with artificial discreplacement which when compared to other surgical prosthesis, such astotal hip and knee replacements, rarely last longer than 15-20 years.Current evidence indicates that spine arthroplasties will improve thatstatistic. It is also well appreciated that spine arthroplasties mayhave a much earlier revision rate than their lower extremitycounterparts.

SUMMARY OF THE INVENTION

In accordance with one or more embodiments of the present invention,methods and apparatus provide for disposing an elongate, tape-likevascular protector and guide at a surgical site and extending a portionthereof from the site at least partially in an anterior lateraldirection prior to closing. For example for lumbar spinal surgeries, thevascular protector and guide is placed near and/or around vascularstructures, and preferably attached towards one end to the lumbarvertebral bones of the spine and at another end to the posterior rectussheath and/or the psoas muscle. The vascular protector and guideoperates as a covering, shroud, and/or membrane that identifies the siteof a previous corrective surgery and protects sensitive vessels of thepatient during a revision surgery to the site.

In preferred embodiments, the vascular protector and guide includes oneor more re-entrant bends to fold over itself before extending theportion to the anteriorly disposed structure (e.g., the posterior rectussheath or psoas muscle for lumbar surgeries). Depending on theparticular surgical site along the spine, the vascular protector andguide may be wrapped partially or fully around, or laid over, one ormore of the great vessels (aorta or vena cava), common iliac arteries,common iliac veins, other blood vessels, the esophagus, etc.

The vascular protector and guide is preferably composed of a syntheticand/or organic material in a pre-cut and formed delivery kit. Forexample, the vascular protector and guide may be composed of a polymer,such as PolyTetraFluoroEthylene (PTFE) (e.g., a Gore-Tex™ membranematerial), Carbon Fiber, highly purified xenograft materials such asbovine, porcine, simian and/or human tissue based collagen-likematrices, and/or other polymer based barrier sheets.

Once in place, the vascular protector and guide creates one or moreidentifiable access points to the surgical site during revision anteriorspinal surgery, thusly reducing the potential injuries to thesurrounding tissues and other structures. More particularly, thevascular protector and guide identifies possible surgical planesincluding potential re-entry sites during the revision procedure.Dissection is preferably carried along the guide as needed to reach theprevious surgical site, reducing the need of blind dissection in theadhered scar tissues.

The vascular protector and guide preferably includes at least one ofvisual indicia and machine readable indicators to assist the surgeon inlocating the guide before and during the revision surgery. For example,the vascular protector and guide may include a fluoroscopic,radio-opaque (e.g., x-ray markers of titanium, tantalum, barium or otheropaque material), or otherwise machine readable marker at one or morelocations along the length thereof to permit the surgeon to identifysuch positions before and during dissection. By way of example, amachine readable marker may be disposed proximate the end of thevascular protector and guide at, e.g., the posterior rectus sheathand/or psoas muscle. This would permit the surgeon to identify thelocation of the guide before and during the incision procedure. The oneor more markers may be imbedded into, impregnated into, laminatedwithin, woven in, sewn in, or otherwise coupled to the guide.

Additionally or in the alternative, the vascular protector and guide mayinclude an array of visually identifiable arrows (or other indicia)extending from the end thereof, e.g., at the posterior rectus sheathtowards the site. This permits the surgeon to dissect along the guidetoward the site, thereby minimizing the damage to surrounding tissue.

Depending on how the vascular protector and guide is placed in proximityto the sensitive structures at the site, the pulling of the guide awayfrom the anterior site may aid in spreading the sensitive structuresaway from the site (as opposed to the difficulty in mobilizing thesensitive structures without the guide placed during the index surgery).Also, depending on how the vascular protector and guide is implanted,retractors may be placed within the medial or lateral folds (dependingupon the level of surgery (e,g., Lateral: L1-2, L2-3, L3-4, L4-5;Medial: L5-S1) and the direction of retraction that is required toassist in identifying and exposing the revision surgery site. Forexample, in the case of a L5/S1 spinal motion segment surgery, thevascular protector and guide may be: (i) extended over the anteriorportion of the subject disk space between the left and right commoniliac arteries and veins; (ii) tacked in at left and right lateralportions of the subject vertebral bones; (iii) folded over itself one ormore times; and (iv) extended and attached to the posterior rectussheath and/or the psoas muscle. If the re-entrant folds of the vascularprotector and guide were well situated with respect to the left andright common iliac arteries and veins during the initial correctivesurgery, retractors may be placed in the folds and the guide may beincised over the disk space to gain entry to the motion segment, duringa revision surgery.

The vascular protector and guide is preferably provided to the surgeonin a variety of geometrically appropriate patterns to accommodatepredetermined anatomical structures. For example, a kit of vascularprotector and guides of differing lengths, widths, and/or thicknessesare preferably provided to bridge different disk space anatomies. It isalso preferred that pre-marked attachment positions are located alongthe vascular protector and guide to assist the surgeon in determiningwhere to attach the guide to the spine (at one end) and/or the posteriorrectus sheath, the psoas muscle, etc., at the other. Additionally oralternatively, one or more predetermined fold lines may be marked on thevascular protector and guide to suggest positions at which re-entrantbends may be provided.

Once implanted, the vascular protector and guide purposely lays nascentuntil an anterior revision procedure is needed. The device permits thesurgeon to reduce possible complications associated with scar relatednavigational errors to the original surgical site. Among the advantagesof the vascular protector and guide are permitting the use of a machineto read one or more marker(s) prior to and during the revision surgeryfor localization and re-entry into the prior surgical site, facilitatingidentification of sensitive anatomical structure(s), facilitatingidentification of surgical planes and safe navigation path(s) aroundcritical structures and through scar laden areas.

Other aspects, features, and advantages of the present invention will beapparent to one skilled in the art from the description herein taken inconjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

For the purposes of illustration, there are forms shown in the drawingsthat are presently preferred, it being understood, however, that theinvention is not limited to the precise arrangements andinstrumentalities shown.

FIG. 1 is a perspective anterior-lateral view of a lumbar region of aspinal column of a patient;

FIGS. 2-3 are anterior views of the lumbar region of the spinal columnas in FIG. 1 where one or more embodiments of a vascular protector andguide are being implanted proximate to the L5/S1 motion segment of thepatient after a corrective surgery has taken place;

FIGS. 4-6 are anterior views of the lumbar region of the spinal columnshowing various embodiments of the vascular protector and guide in afurther implantation position;

FIGS. 7-9 are anterior and anterior-lateral views of the lumbar regionof the spinal column where one or more further embodiments of thevascular protector and guide are being implanted proximate to the L4/L5motion segment; and

FIG. 10 is an anterior view of the cervical region of the spinal columnwhere one or more further embodiments of the vascular protector andguide are being implanted proximate to esophagus of the patient.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the drawings, wherein like numerals indicate likeelements, there is shown in FIG. 1 an anterior perspective view of thehuman sacral-lumbar spinal column showing an exposure of some motionsegments thereof. The illustration shows a subset of the anatomy,including several of the vertebral bodies 10 of the spine, the aorta 12,the vena cava 14, the left and right common iliac arteries 16, 18, andthe left and right common iliac veins 20, 22. For the purposes ofdiscussion, it is assumed that a repair, reconstruction, etc. of theL5/S1 motion segment 30 has been completed and the ligament 28 has beenrepaired. As discussed above, the repair or reconstruction may include adisk fusion, vertebral cage implantation, artificial disk replacement,etc.

Under conventional protocols, the surgeon would begin closing proceduresafter the motion segment 30 and ligament 28 have been repaired. Inaccordance with one or more embodiments of the present invention,however, the surgeon will first implant a vascular protector and guide100 (best seen in FIG. 2 et seq.) before closing the site. Onceimplanted, the guide 100 operates, at least in part, to assist a surgeonin a subsequent surgery to the same motion segment 30. As white, densescar tissue will develop after a first surgical procedure to the motionsegment 30, without the guide 100, it would be difficult to navigatethrough the scar tissue during a re-entry surgical procedure. Indeed,when navigating through a scar tissue mass during a re-entry procedure,it is off paramount concern that the surgeon does not damage the bloodvessels that may be near or in the scar tissue, such as the aorta 12,the vena cava 14, the left and right common iliac arteries 16, 18, andthe left and right common iliac veins 20, 22.

The vascular protector and guide 100 preferably operates to produce oneor more planes through a scar laden field, and the surgeon may navigatealong the guide 100 during the subsequent revision surgery. As thevascular protector 100 guides the surgeon through the scar tissue mass,the delicate blood vessels are less susceptible to injury and the priorsurgical site at the motion segment 30 may be more easily, quickly andcleanly exposed for the revision surgery.

With reference to FIG. 2, a retroperitoneal exposure of the L5/S1 motionsegment 30 (obscured by the ligament 28) of the spine is illustrated inwhich one embodiment of the vascular protector and guide 100 is beingimplanted. Much of the anatomy illustrated in FIG. 1 is also shown inFIG. 2. Some segmental vessels 26 are shown as being transected andligated. The vascular protector and guide 100 is preferablynon-biodegradable, not-bio-absorbable, and pliable with a relatively lowflex modulus such that it is easily bendable by hand. For example, thevascular protector and guide 100 may be composed of a polymer, such asPolyTetraFluoroEthylene (PTFE) (e.g., a Gore-Tex™ membrane material), apolyurethane (such as or Carbothane), carbon fiber, highly purifiedxenograft such as bovine, porcine, simian or human tissue basedcollagen-like matrices, other polymer based barrier sheets, or any otherassorted materials well known to surgeons.

The guide 100 includes and elongate, flexible body having first andsecond terminal ends 102, 104. The first end 102 is coupled to at leastone vertebral body 10A, such as the S1 and/or the L5 vertebral bodies.By way of example, the vascular protector and guide 100 may be tacked tothe vertebral body 10A using commonly available biologically acceptablesurgical staple(s), tack(s), adhesive(s), or any other of the known ofhereinafter developed attachment mechanisms. In one or more embodimentsof the invention, a first tack or staple 106 may be used to attach thevascular protector 100 to the S1 vertebral body, while a second tack orstaple 106 may be used to attach the vascular protector to the L5vertebral body. It is noted that the tacks 106 may be located relativelyclose to the first end 102 of the vascular protector 100. Those skilledin the art will appreciate that other attachment techniques presentlyknown or hereinafter developed may be employed to attach the vascularprotector to the motion segment.

Given that, in this example, the surgical repair site is the L5/S1motion segment, the first end 102 of the guide 100 may be attached tothe at least one vertebral body 10A proximal to one of the left andright common iliac arteries 16, 18 or veins 20, 22. In the illustrationof FIG. 2, the first end 102 of the guide 100 is attached to the L5 andS1 vertebral bodies proximal to the left common iliac artery 16 and vein20.

With Ref. to FIG. 3, the vascular protector and guide 100 is preferablyextended over at least a portion of the surgical repair site. In theillustrated example, the guide 100 is extended from the first end 102 atleast partially laterally along the anterior L5/S1 motion segment to theright common iliac artery 18 and vein 22. The vascular protector andguide 100 is then preferably attached (e.g., via tacks 108) to the atleast one vertebral bone 10A. In accordance with one or more embodimentsof the invention, the guide 100 may include one or more visual indiciasuggesting to the surgeon where along the guide 100 to attach to thespine.

In accordance with one or more embodiments of the invention, as seen inFIG. 4, the guide 100 may be folded at least partially over itself oneor more times in the manner of an accordion substantially between theleft and right common iliac arteries 16, 18 or veins 20, 22. In thisregard, the surgeon may determine the one or more fold positions,intermediate to the first and second ends 120, 104, based on thepatient's anatomy. Alternatively or in addition, the guide 100 mayinclude one or more visual fold lines suggesting to the surgeon where tofold the guide 100 to accommodate a suitable implantation position. In afurther alternative embodiment of the invention, the guide 100 may bepre-formed into a geometrically appropriate pattern to accommodate apredetermined anatomical structure, such as the aforementioned accordionarrangement and/or one or more other arrangements discussed and/orsuggested herein. The significance of the accordion arrangement will bediscussed later in this description.

FIG. 4 illustrates the accordion arrangement of the vascular protectorand guide 100 when the first end 102 of the guide 100 is disposed towardor under the left common iliac artery 16 and/or vein 20. As suggestedabove and as shown in FIG. 5, an alternative embodiment of the presentinvention may provide for the first end 102 of the guide 100 beingcoupled to the at least one vertebral body 10A toward the right commoniliac artery 18 and/or vein 22. If desired by the surgeon, the guide 100may be folded over itself one or more times as discussed previously.

Irrespective of the starting position of the first end 102, somedistance between the terminal end 102 of the vascular protector 100 andthe tacks 106 may be provided to produce a flap 112. The flap 112 may bedisposed between: (i) the at least one vertebral body 10A and the leftcommon iliac artery 16 and/or vein 20 (FIG. 4); or (ii) the at least onevertebral body 10A and the right common iliac artery 18 and/or vein 22(FIG. 5). In the arrangement of FIG. 4, the flap 112 lays substantiallystraight (not folded) between the vertebral body and the left commoniliac artery 16 and/or vein 20. In contrast, the arrangement of FIG. 5shows the flap 112 folded in re-entry fashion to overlay itself whilebeing disposed between the vertebral body and the right common iliacartery 18 and/or vein 22. Depending on its length, the flap 112 mayoverly at least a portion of a blood vessel, such as the right commoniliac artery 18 or vein 22, as may be achieved by folding the flap 112of FIG. 5 over the artery 18 or vein 22. Alternatively, the flap 112 ofFIG. 4 may be extended as shown in FIG. 6 to overly the left commoniliac artery 16 and/or vein 20. FIG. 6 also illustrates a furtheralternative configuration in which a portion of the guide 100 extends(circumferentially) under and around, for example, the right commoniliac artery 18 and/or vein 22.

It is noted that in alternative embodiments, the flap 112 need not beprovided. Suffice it to say that those skilled in the art willappreciate from the description herein that the variations as to theorientation of the guide 100 in and around the vessels in accordancewith the present invention are too numerous to list in their entirety.

Although intermediate portions, between the first and second ends 102,104 of the guide 100 may be oriented in various ways depending on thespecific anatomy of the patient and other factors (such as the accordionarrangement), the second end 104 of the guide 100 is preferably extendedand coupled a structure of the patient spaced in an anterior directionaway from the at least one vertebral body 10A towards an entry incision.When implanting the guide 100 in at least the lumbar region of thespine, the structure to which the second end 104 is coupled may be theposterior rectus sheath, the psoas muscle, etc. Such attachment may beachieved via sutures, clips, etc.

Once implanted, the vascular protector and guide 100 purposely laysnascent until an anterior revision procedure is needed. The devicepermits the surgeon to reduce possible complications associated withscar related navigational errors to the original surgical site.Preferably, the vascular protector and guide 100 permits the use of amachine to read one or more marker(s) prior to and during the revisionsurgery for localization and re-entry into the prior surgical site. Inthis regard, the guide 100 preferably includes one or more machinereadable indicators 120 (FIG. 5), such as one or more fluoroscopicmarkers, and/or one or more radio-opaque markers, disposed at one ormore locations along a length of the guide 100. By way of example, theone or more radio-opaque markers may be x-ray markers formed fromtitanium, tantalum, and/or any of the other known materials. Preferably,the one or more machine readable markers 120 are disposed proximate thesecond end 104 of the vascular protector and guide 100 such that thesurgeon may identify the location of the second end 104 before anincision procedure. Alternatively, an array of such markers 120, e.g.,along a significant length thereof, the may permit the surgeon tocompare postoperative AP and a subsequent x-ray and determine whether ornot the guide 100 has migrated. This may be particularly useful if oneis contemplating repeat anterior surgery.

Irrespective of whether the machine readable marker(s) 120 are employed,the reentry procedure preferably includes utilizing the prior skinincision, the previous facia incision, and location of the second end104 of the vascular protector and guide 100. Next, the surgeonpreferably dissects down along the vascular protector and guide 100,which identifies sensitive anatomical structure(s), surgical planes andsafe navigation path(s) around critical structures and through scarladen areas.

Preferably, the guide 100 includes one or more visual indicia 122 thatassist the surgeon during the re-entry surgery. For example, the visualindicia 122 may include an array of arrows extending from the second end104 of the guide 100 towards the first end 102 such that the arrowsassist the surgeon in dissecting along the guide 100 toward the site.

Assuming that one of the accordion arrangement of FIGS. 4-6 (or any ofthe various alternatives suggested herein) was employed during theinitial corrective surgery, upon the re-entry to the site, the guide 100may be pulled in an anterior direction such that the guide at least oneof: unfolds in the manner of an accordion, spreads the left and rightcommon iliac arteries and/or veins, and exposes the site. Thus, thesurgeon may carefully unwrap or pull the vascular protector 100 awayfrom the spine to expose the site. Vessel retraction, removal of thevascular protector 100, and the revision surgery on the spine may thentake place. After the revision surgery to the spine is complete, a newvascular protector 100 may be implanted utilizing the techniquesdiscussed above and/or herein below.

As mentioned above, those skilled in the art will appreciate from thedescription herein that the variations as to the orientation of theguide 100 in accordance with the present invention numerous. While theexamples illustrated and described herein generally relate to ananterior orientation of the guide 100, the surgical site, and thereforethe guide 100, may be located anteriorly, anterior-laterally, in acostotransverse position, and/or in an extracavitary of the spinalcolumn. Thus, for example, the vascular protector 100 also has utilityin protecting blood vessels that are, for example, laterally located.

In accordance with one or more further embodiments of the presentinvention, the vascular protector and guide 100 may be utilized at otherportions of the spine, for example, in other portions of the lumbarand/or thoracic spine. By way of illustration, FIGS. 7-9 show the guide100 being employed at the L4/L5 motion segment, which is where many, ifnot most, of the vascular injuries occur, particularly, during revisionsurgeries. The surgeon may retract 130 the aorta 12 and the vena cava 14(FIG. 7), position a portion of the guide 100 between at least onevertebral body 10B and one or more blood vessels (e.g., the aorta 12 andthe vena cava 14) and coupling the guide 100 to the at least onevertebral body 108 (FIG. 8). As best seen in FIG. 9, a flap 112 may beprovided by coupling the guide 100 at an intermediate position away fromthe first end 102, folding the guide 100 at a position between theintermediate position and the first end 102, and positioning the flap112 to overly at least a portion of the one or more blood vessels.Alternatively or in addition, the fold may be a re-entrant bend and theflap 112 may be extended over itself and over lateral and anteriorportions of the one or more blood vessels.

Those skilled in the art will appreciate that the technique and use ofthe guide 100 described above with respect to the L4/L5 motion segmentmay be readily applied to other areas of the spine (anteriorly,anterior-lateral, etc.) including the thoracic spine. When used in thethoracic spine, the second end 104 of the guide 100 is preferablyextended at least in an anterior direction prior to closing tofacilitate guiding the surgeon during a revision surgery, if needed.Preferably, the end 104 of the guide 100 terminates at (or is coupledto) the posterior, costal periosteum (rib periosteum) of the patient.

In addition, the vascular protector 100 may be used to treat the effectsof scar tissue forming between the esophagus and the cervical spine. Forexample, a prior surgery to the cervical spine, an infection, and/orradiation treatments may induce the formation of scar tissue between thecervical spine and the esophagus. This scar tissue may cause dysphagia,which disrupts the swallowing processing and is a serious health risk asit may lead to aspiration pneumonia, malnutrition, dehydration, weightloss, and airway obstruction. Use of the vascular protector 100 in thecervical spine, however, results in less dissection on reentry and,therefore, less chance of dysphagia. As shown in FIG. 10, the vascularprotector and guide 100 may be disposed in the cervical region of thespinal column by positioning a portion of the guide 100 between at leastone vertebral body and the esophagus 124 of the patient prior tocoupling the guide 100 to the vertebral body. As with other embodimentsherein, the guide 100 may be used to provide a flap 112 to overly atleast a portion of the esophagus 124. Again, the guide 100 may be sizedand shaped to accommodate the particular anatomy, in this example thecervical spine.

When used in the cervical spine, the second end 104 of the guide 100 isalso preferably extended at least in an anterior direction prior toclosing. Preferably, the end 104 of the guide 100 terminates at (or iscoupled to) the superficial cervical fascia or platysma of the patient.

Again, the advantages of the vascular protector and guide 100 includepermitting the use of a machine to read one or more marker(s) prior toand during the revision surgery for localization and re-entry into theprior surgical site, facilitating identification of sensitive anatomicalstructure(s), facilitating identification of surgical planes and safenavigation path(s) around critical structures and through scar ladenareas.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1-27. (canceled)
 28. An apparatus for identifying and guiding a surgeonduring a re-entry surgery to a site of a spinal column at whichcorrective surgery has previously taken place, the spinal columnincluding a first vertebral body and, a second vertebral body, theapparatus comprising: an elongate relatively thin flexible guide havinga width and a length between first and second ends, the first end beingcouplable to the first vertebral body with a first attachment mechanismand to the second vertebral body with a second attachment mechanism, thesecond end spaced away from the spinal column towards an entry incision,the elongate flexible guide having a first intermediate fold between thefirst and second ends, the first intermediate fold being along the widthof the guide so that when implanted the fold is oriented generallyparallel to a cranial-caudal direction of the spinal column; and atleast one of: (i) one or more visual indicia, and (ii) one or moremachine readable indicators, operable to assist a surgeon in locatingthe guide before and during the re-entry surgery, the at least one ofthe one or more visual indicia and one or more machine readableindicators extending from the second end toward the first end.
 29. Theapparatus of claim 28, wherein the visual indicia includes an array ofarrows extending from the second end of the guide towards the first endsuch that the surgeon may dissect along the guide toward the site duringthe re-entry surgery.
 30. The apparatus of claim 28, wherein the machinereadable indicia includes at least one of: (i) one or more fluoroscopicmarkers, and (ii) one or more radio-opaque markers, disposed at one ormore locations along a length of the guide to permit the surgeon toidentify such positions before and during dissection.
 31. The apparatusof claim 30, wherein the one or more radio-opaque markers are x-raymarkers formed from at least one of titanium, tantalum, and barium. 32.The apparatus of claim 30, wherein the one or more machine readablemarkers may be disposed proximate the second end of the guide such thatthe surgeon may identify the location of the second end of the guidebefore an incision procedure.
 33. The apparatus of claim 28, wherein theguide is formed from at least one of a polymer, a carbon fiber, apurified xenograft material, purified bovine based collagen matrices,purified porcine based collagen matrices, purified simian basedcollagen-like matrices, and purified human tissue based collagenmatrices.
 34. The apparatus of claim 33, wherein the polymer isPolyTetraFluoroEthylene (PTFE).
 35. The apparatus of claim 28, whereinthe guide is pre-formed into a geometrically appropriate pattern toaccommodate a predetermined anatomical structure.
 36. The apparatus ofclaim 35, wherein the geometrically appropriate pattern includes avisual indicia indicative of at least one of: a suggested fold line toaccommodate an accordion implantation position with respect to the atleast one vertebral body; and an attachment position along the guide foridentifying a position at which to attach the guide to the at least onevertebral body.
 37. The apparatus of claim 28, wherein the first andsecond attachment mechanisms include at least one of biologicallyacceptable surgical staples, tacks, and adhesives.